'The basis on which Christians can speak to one another is that each knows the other as a sinner who, even given all one’s human renown, is forlorn and lost if not given hep. This does not mean that the others are being disparaged or dishonoured. Rather, we are paying them the only real honour a human being has, namely, that as sinners they share in God’s grace and glory, that they are children of God. This realization gives our mutual speech the freedom and openness it needs. We talk to one another about the help we both need. We admonish one another to go the way Christ bids us to go. We warn one another against the disobedience that is our undoing. We are gentle and we are firm with one another, for we know both God’s kindness and God’s firmness. Why should we be afraid of one another since both of us have only God to fear?’
‘Nothing can be more cruel than that leniency which abandons other to their sin. Nothing can be more compassionate than that severe reprimand which calls another Christian in one’s community back from the path of sin.’
More Bonheffer quotes here.